1. Field of the Invention
The present invention relates to an image pickup (photographic) apparatus such as a video camera and, more particularly, to an image pickup apparatus in which a lens unit is interchangeable with respect to a camera main-body unit.
2. Related Background Art
A conventional video camera arranged as a camera built-in VTR cannot generally interchange lenses. As in a still camera using a silver chloride film, it is not easy to perform telephoto or wide-angled photography, thus narrowing a photographic range. A camera built-in VTR having interchangeable lenses is recently available on the market. However, this VTR does not have an auto-focus (AF) function and an auto-iris (auto-exposure or AE) function.
The present inventors have made extensive studies on developing a lens-interchangeable video camera having a lens unit which incorporates a photographic lens and an iris and which is detachable and interchangeable with respect to a camera main-body unit incorporating an image pickup element. In this video camera, a control unit including a microcomputer is arranged in each of the camera main-body unit and a lens unit. When the camera main-body unit is connected to the lens unit, the control units therein are connected through a data transmission line (communication line). In the camera main-body unit, a field brightness value from an image pickup element is detected, and an exposure operation is performed by the control unit in the camera main-body unit on the basis of the detected field brightness value. This exposure operation result is transmitted to the control unit in the lens unit. The control unit in the lens unit determines an iris opening amount on the basis of the exposure operation result and drives an iris driving means in accordance with the determined opening amount. The band of the field brightness signal in the camera main-body unit is limited by a plurality of band-pass filters. A focus operation of the control unit in the camera main-body unit is performed on the basis of the band-limited signal, and the operation result is transmitted to the control unit in the lens unit. The direction and speed of a focus motor are determined on the basis of the focus operation result in the control unit in the lens unit. A focus driving means is driven in accordance with the determined direction and speed.
In the lens-interchangeable image pickup apparatus having the exposure control system and the focus control system described above, when a user or photographer keeps disconnecting the lens unit from the camera main-body unit while the power switch of the lens unit is kept on, wasteful power is consumed, and a photographic time is undesirably shortened. Since electrical contacts of the mounting unit are exposed to the outer air, when the electrical contacts are short-circuited, the camera main-body unit is undesirably damaged.
In the lens-interchangeable video camera, picture recording is performed while the lens is properly mounted. If the lens is detached from the main-body or incomplete electrical connections occur between the lens and the camera main-body, the lens is set in an uncontrollable state. At this time, when the user erroneously touches a pushbutton type picture recording switch, an unnecessary picture is recorded although an optimal photographic operation cannot be performed. In this case, in order to erase the unnecessary recorded portion, a predetermined operation such as rewinding must be performed.
In the lens-interchangeable video camera, when the picture recording switch is touched in a lens uncontrollable state, picture recording is performed in a state except for the optimal photographic state, a cumbersome operation such as erasure of the unnecessary recorded portion must be undesirably performed.
The present invention has been made in consideration of the above problems, and has as its first object to provide an lens-interchangeable image pickup apparatus which can reduce wasteful power consumption upon detachment of a lens unit from a camera main-body unit and which does not damage the camera main-body unit even if electrical contacts of a mounting unit are accidentally short-circuited.
It is the second object of the present invention to provide an image pickup apparatus wherein a state of a lens unit attached to or detached from a camera main-body unit is determined and a switching means for supplying a drive power supply voltage from a main power supply in the camera main-body unit to each portion is controlled on the basis of the determination result, wasteful power consumption upon detachment of the lens unit from the camera main-body unit can be reduced, and damage to the camera main-body unit can be prevented even if electrical contacts of a mount unit are accidentally short-circuited.
In order to achieve the first and second objects according the present invention, there is disclosed an image pickup apparatus comprising a camera main-body unit, a lens unit detachable from the camera main-body unit, attachment/detachment determining means for determining a state of the lens unit attached to or detached from the camera main-body unit, switching means for supplying a drive power supply voltage from a main power supply in the camera main-body unit to each portion, and control means for controlling the switching means in accordance with a determination result from the attachment/detachment determining means.
The attachment/detachment determining means determines the state of the lens unit attached to or detached from the camera main-body unit, and the control means controls the switching means for supplying the drive power supply voltage from the main power supply in the camera main-body unit to each portion on the basis of the determination result.
The present invention has also been made in consideration of the conventional problems described above, and has as its third object of the present invention to provide a lens-interchangeable image pickup apparatus which can prevent a wasteful flow of a drive current when a lens unit is kept detached from a camera main-body unit, which has low power consumption, and which can prolong a photographic time.
It is the fourth object of the present invention to provide an image pickup apparatus wherein a state of a lens unit attached to or detached from a camera main-body unit is determined, a driving means for changing a focus state of a light-receiving surface of an image pickup element is controlled to stop the driving means upon detachment of the lens unit from the camera main-body unit, so that a wasteful flow of a drive current upon detachment of the lens unit from the camera main-body unit can be reduced, and the photographic time can be prolonged.
In order to achieve the third and fourth objects of the present invention, there is provided an image pickup apparatus comprising a camera main-body unit having an image pickup element, a focus-controllable lens unit detachably mounted on the camera main-body unit, attachment/detachment determining means for determining a state of the lens unit attached to or detached from the camera main-body unit, driving means for changing a focus state of a light-receiving surface of the image pickup element, and control means for controlling the driving means, wherein the driving means is disabled when the lens unit is detached from the camera main-body unit, so that the state of the lens unit attached to or detached from the camera main-body unit can be determined, and the control means controls the driving means for changing the focus state of the light-receiving surface of the image pickup element, whereby the driving means is disabled when the lens unit is detached from the camera main-body unit.
It is the fifth object of the present invention to provide an image pickup apparatus capable of reducing wasteful power consumption upon detachment of a lens unit from a camera main-body unit, prolonging a photographic time, and changing a focus state of a light-receiving surface of an image pickup element by appropriate driving upon attachment of the lens unit to the camera main-body unit.
It is the sixth object of the present invention to provide an image pickup apparatus capable of reducing wasteful power consumption upon detachment of a lens unit from a camera main-body unit, prolonging a photographic time, and changing a focus state of a light-receiving surface of an image pickup element by an appropriate drive amount upon attachment of the lens unit to the camera main-body unit.
In order to achieve the fifth and sixth objects of the present invention, there is disclosed an image pickup apparatus a camera main-body unit having an image pickup element, a focus-controllable lens unit detachably mounted on the camera main-body unit, attachment/detachment determining means for determining a state of the lens unit attached to or detached from the camera main-body unit, driving means for changing a focus state of a light-receiving surface of the image pickup element, and control means for controlling the driving means in accordance with a determination result from the attachment/detachment determining means, wherein the driving means is controlled by the same drive amount as required during manual focus control when the lens unit is detached from the camera main-body unit, so that the state of the lens unit attached to or detached from the camera main-body unit can be determined by the attachment/detachment determining means, and the control means controls the driving means for changing the focus state of the light-receiving surface of the image pickup element, whereby the driving means is controlled by the same drive amount as required during manual focus control when the lens unit is detached from the camera main-body unit.
It is the seventh object of the present invention to provide an image pickup apparatus capable of easily detecting a state of a lens unit attached to or detached from a camera main-body unit, preventing a photographic failure, and preventing a user or photographer from feeling anxiety or discomfort.
In order to achieve the seventh object of the present invention, there is provided an image pickup apparatus comprising a camera main-body unit, a lens unit detachable from the camera main-body unit, attachment/detachment determining means for determining a state of the lens unit attached to or detached from the camera main-body unit, video signal generating means for outputting a desired video signal, switching means for switching between the video signal and the picked video signal, and control means for controlling the switching means in accordance with a determination result from the attachment/detachment determining means, wherein the desired video signal not associated with the image pickup signal is output when the lens unit is detached from the camera main-body unit, thereby preventing an output of uncomfortable noise on a picture.
In order to achieve the above object according to the present invention, there is disclosed an image pickup apparatus comprising a camera main-body unit having an image pickup element, a focus-controllable lens unit detachably mounted on the camera main-body unit, attachment/detachment determining means for determining a state of the lens unit attached to or detached from the camera main-body unit, a gate circuit for performing the focus control in an arbitrary area in an image pickup frame, an focus frame generation circuit for outputting a focus frame signal for displaying the arbitrary area, and a control unit for controlling the focus frame generation circuit in accordance with a determination result from the attachment/detachment determining means, wherein the state of the lens unit attached to or detached from the camera main-body unit can be easily detected in accordance with a state of the focus frame.
It is the eighth object of the present invention to provide a lens-interchangeable video camera which prohibits picture recording in a lens uncontrollable state and eliminating a cumbersome operation for erasing an unnecessary portion.
In order to achieve the eighth object of the present invention, there is disclosed a video camera having a photographic lens detachably mounted on a camera main-body unit, comprising means for discriminating a state of the lens as a lens controllable or uncontrollable state, and control means for prohibiting picture recording when the lens is set in the uncontrollable state, wherein the discriminating means discriminates that the lens is in the lens controllable or uncontrollable state, and picture recording is prohibited when the lens is set in the lens uncontrollable state.
It is the ninth object of the present invention to provide a lens-interchangeable video camera wherein picture recording is set in a waiting state when the lens is set in a lens uncontrollable state, and a cumbersome operation for erasing the unnecessary part need not be performed.
In order to achieve the ninth object of the present invention, there is provided a video camera having an image pickup lens detachably mounted on a camera main-body unit, comprising means for discriminating a state of the lens as a lens controllable or uncontrollable state, and control means for setting picture recording in a waiting state during picture recording when the lens is set in the uncontrollable state, wherein the discriminating means discriminates that the lens is in the lens controllable or uncontrollable state, and picture recording is set in the waiting state when the lens is set in the lens uncontrollable state.
It is the tenth object of the present invention to provide a video camera apparatus effectively used in, particularly, a camera built-in video tape recorder for outputting a warning display during reproduction of recorded information without degrading the picture quality since the warning display is performed during detachment of a lens unit from a camera main-body unit upon detection of attachment/detachment of the lens unit so as to easily and accurately determine the lens attachment state, and since whether a lens detachment warning message is displayed is selected in accordance with a mode of the apparatus.
It is the eleventh object of the present invention to provide a video camera apparatus wherein lens mounting is detected by using two detecting means, reliability of detection can be improved, and at the same time, contamination and defects of contacts, and the lens failure can be easily found.
In order to achieve the tenth and eleventh objects of the present invention, there is disclosed an interchangeable lens type camera apparatus comprising a lens unit, a camera main-body unit on which the lens is detachably mounted, means for detecting a state of the lens unit attached to or detached from the camera main-body unit, means for determining whether a warning display is performed when the detachment of the lens unit is detected by the detecting means, and display means for performing the warning display on the basis of an output from the determining means.
In order to achieve the tenth and eleventh objects of the present invention, there is also disclosed an interchangeable lens type camera apparatus comprising a lens unit, a camera main-body unit on which the lens unit is detachably mounted, communicating means for transmitting driving control information from the camera main-body unit to the lens unit and sending back information representing an operating state of the lens unit to the camera main-body unit, first detecting means for detecting an attachment state of the lens unit with respect to the camera main-body unit, second detecting means for detecting an attachment state of the lens unit with respect to the camera main-body unit through the communicating means, and display means for performing a warning display when the state of the lens unit detached from the camera main-body unit is detected on the basis of the detection results from the first and second detecting means.
The above and other objects, features, and advantages of the present invention will be apparent from the detailed description of the present invention in conjunction with the accompanying drawings.